Enhancing biomass productivity towards carbohydrates and fatty acids biosynthesis under the effects of magneto-electric composite fields on filamentous algae

Abstract

Filamentous algae from the genus Tribonema presents a challenge in commercial applications because of their slow growth and low oil content. Magneto-electric composite fields (MECs) intervention has been used to increase the development of several plants; however, its effects on algal metabolism are unclear. Here, the Tribonema sp. was cultured under the interventions of ME (24/d-0.6V/cm, 1h/d-0.6V/cm, 24h/d-1.2V/cm, 1h/d-1.2V/cm) as well as individual MF or EF and control conditions. The objectives are to provide a comparative analysis of individual MF or EF and their synergistic (coupling) effects on biomass accumulation and conversion to fatty acids. The maximum increase in biomass (21.54%), carotenoid (15.9%), carbohydrate (23.1%), and lipids (4.5%) were obtained at 1h/d-0.6V/cm. The productivities (mgL−1d−1) of biomass, carbohydrate, and lipids were increased by 31%, 55%, and 47%, respectively, compared to their controls. For 1h/d-1.2V/cm intervention, palmitic acid and palmitoleic acid showed an increase of 24.5% and 45.9%, respectively. Furthermore, fatty acids showed improved biodiesel characteristics, including long-chain saturated factor and cold filter plugging point. Genes encoding glycolytic enzymes: Hexokinase, Triose phosphate isomerase, 6-phosphofructokinase, Pyruvate dehydrogenase upregulated or 1h/d-.2V/cm. Fatty acid biosynthetic enzymes: Fatty acid synthase, Acyl-carrier-protein - S-malonyltransferase, 3-oxoacyl-ACP-synthase II, 3-oxoacyl-ACP reductase, Enoyl- ACP reductase I, upregulated uunder 1h/d-0.6V/cm, together with downregulation of fatty acids degradation genes. This study, for the first time, provided MECs as an efficient stimulus toward the conversion of carbohydrates into fatty acids in Tribonema for the production of eco-friendly and cost-effective energy.